Polarized control apparatus



1949 A. T. JOHNSTON ET AL 2,461,060

POLARI ZED CONTROL APPARATUS Filed July 51, 1946 W INVENTORS' 4 i/ Allan If Jzozz and RA BYAP LJafiome.

THEIR ATTORNEY.

Patented Feb. 8, 1949 UNITED STATES PATENT OFFICE 2,461,060 POLARIZED CDNTROL APPARATUS Allan r. Johnston, Mount Lebanon, and Arthur L. Jerome, Edgewood, Pa., 'ass'ignor's to The Union Switch &

Signal Company, Swissvale,

Pas a corporationof Pennsylvania Application July 31, 1946, Serial No. 687,482

7 Claims.

Our invention relates to electrical control apparatus, and particularly to apparatus for effecting one nmcuo'n'when a control circuit is energized by current of one relative polarity and another function when the control circuit is energized by current of the other'relative'polarity.

The apparatus of this invention is an improvement "on that shown and claimed in Letters Patent of the United States No. 2,340,752, granted February 1, 1944, to Andrew Hufnagel,

In the Hufna'gel patent there is shown control apparatus having a polar "relay energized over a control circuit, an auxiliary relay associated with the polar relay and energized from the control circuit over connections governed by contacts of the polar relay, and having means efiectiv'e on a change in the polarity of the energy supplied to the control circuit to-maintain the contacts of the auxiliary relay picked up during movement of the contacts from one position to the other.

It is an object of this invention to provide improved control apparatus of the type described and in which the retained neutral feature may be eliminated.

Another object of this invention is to provide improved control apparatus for controlling electric motors for operating track switches.

A further object of this invention is to provide improved control apparatus for alternating current electric switch motors wherein positive releasing of the overload relay as a result of a change of polarity of the control circuit is provided. v i

We shall describe three forms of control apparatus embodying our invention, and shall then point out the novel features thereof in claims.

In practicing our invention we provide a polar relay and a neutral or polar biased neutral auxiliary relay and energize them from a polarized control circuit. The winding" of the auxiliary relay is reversibly connected across the control circuit by means of polar contacts on the polar relay. The polar and auxiliary relays are selected so that on a change in the polarity of the energy supplied to the control circuit the contacts of the auxiliary relay will release before the contacts of the polar relay respond, while a contact of the auxiliary relay when released establishes a circuit independent of the winding of the auxiliary relay for supplying energy from the control circuit to the winding of the polar relay to operate the polar relay. The circuit governed by thiscont act of the auxiliary relay may shunt the winding of the auxiliary relayto prevent picking up of the auxiliary relay contacts until the polar relay re 2 sponds and may have an asymmetric unit included therein to prevent flow of energy in the circuit when the polar relay contacts and the polarity of the energy supplied to the control circuit are in correspondence.

In some modifications the relaysare employed to control the motor for a track switch, and in these cases an overload relay interrupts the circuit of th auxiliary relay in the event offan overload, while means are provided to release the overload relay on a subsequent change in the polarity of the energy supplied to the control circuit. I g

In thedrawings,Fig 1 is a diagram illustrating one embodiment of our invention,

Fig. 2 is a diagram illustrating a modification of our invention arranged to control a direct current switch machine motor, and v Fig. 3 is a diagram illustrating a modification of our invention arranged to control an alternating current switch machine motor.

Similar reference characters refer to similar parts in each of the three views.

Referring to Fig. 1 of the drawings, the referen'ce character P designates a polar relay, while the reference character N designates an auxiliary relay. The windings of the relays P and N are energized in series over a polarized control circuit here shown as comprisin conductors l8 and H which are cormected by contacts 8 and 9 of a pole changer PC with a suitable source of direct current, such as a battery the terminals of which are designated and The conductors I 6 and H may be line wires, or they may be the track rails of a section oi railway track, while the pole changer PC may be a manually operated device, itmay be the contacts of a relay, or it may be any other suitable mechanism.

The conductor Ill is connected to one terminal of the winding of relay P, while conductor II is connected to polar contact l2 of relayP. The other terminal of the winding of relay P is connected to its polar contact IS. The contacts l2 and [5 control connections for reversibly connecting the winding of the relay N in series with the winding of the relay P,

v The relay N may be of the polar biased type as here shown and if such its contacts become picked up when and only when energy flows through the relay winding in the direction indicated by the arrow. The various parts of the apparatus are the relay N picks up only when the positive terminal of the source is connected to the left-hand terminal of the relay winding.

The rectifier K is connected across the tcr- '3 minals of the relay N by a circuit which is interrupted by a back contact of relay N. The rectifier K is poled to permit energy to fiow in the direction opposite to that which is effective to pick up the contacts of relay N.

The contact I5 of relay N and contact ll of relay P may cooperate to perform any desired control function.

When the equipment is in the condition shown in Fig. 1 of the drawings, energy from the posi' tive terminal of the source flows over pole changer contact 8, through conductor Ill, winding of relay P, and normal polar contact I5 of relay P to the left-hand terminal of relay N, through the winding of relay N, normal polar contact I2 of relay P, conductor II, and pole changer contact 9 to the negative terminal of the source. Atthis time relay P and relay N are energized in series, while the polarity of the energy supplied is such that the contacts of relay P are held in their lefthand position as shown, and the direction of flow of energy through the winding of relay N is that which is effective to pick up the contacts of the relay. The circuit for rectifier K is open at contact I8 of relay N. 7

On a reversal of the pole changer PC the positive terminal of the source is connected by contact 8 to conductor ll and the negative terminal of the source is connected by contact 9 to conductor I0. At the time of reversal of the pole changer PC contacts I2 and I5 of relay P are in their left-hand positions, as shown, so that energy flows from the positive terminal of the source over conductor II and contact I2 of relay P to the right-hand terminal of the winding of relay N, through the relay winding, contact I5 of relay P, winding of relay P, and conductor Hi to the negative terminal of the source.

The energy flowing in this direction through the winding of relay N causes relay N to release due to the reversal of current flow in the winding, which causes the magnetic flux in the relay core to decrease to zero and build up again in the opposite direction. Back contact I6 of relay N closes, and thereby establishes the circuit through rectifier K, shunting relay N. This circuit prevents relay N from picking up and provides a low resistance circuit for the energy supplied to relay P so that its contacts are certain to move. As

soon as contacts I2 and I5 of relay P move out of engagement with their left-hand contacts, the circuit previously traced for energizing the windings of relays P and N is interrupted, but the operating characteristics of the relay P are such that the relay contacts will continue to move after the interruption of the supply of energy to the relay winding with the result that the relay contacts will complete their movement to their righthand positions.

When the contacts of relay P complete their movement to their right-hand positions, a circuit is completed to energize the windings of relays P and N in series. This circuit may be traced from the positive terminal of the source, through pole changer PC, conductor I I, reverse polar contact I 2 of relay P, the winding of relay N from left to right, reverse polar contact I5 of relay P, through the winding of relay R, and over conductor Iii to the pole changer PC and the negative terminal of the source. Although the circuit including rectifier K is closed at this time, the direction of the flow of energy is opposite to the direction in which the recifier is poled, thus no current can flow through the rectifier.

The direction of current flow through the wind- 4 ing of relay N is now such that relay N picks up its contacts, and the circuit including rectifier K is interrupted by back contact I8 of relay N, In addition, the energy supplied to the winding of relay P is effective to maintain the contacts of this relay in their right-hand positions.

The operation of the equipment on a subsequent change in the polarity of the energy supplied over the conductors I t and I I is similar to that described in detail above and will not be repeated.

If, on a change in polarity of the energy supplied over the conductors Ii! and II, the contacts of relay P fail to move from one position to the other, the conductors Ill and it will be connected to the winding of relay N in such a manner that the positive terminal of the source is connected to the right-hand terminal of the relay winding. Accordingly, the direction of flow of energy through the winding of relay N will be such that the energy is ineifective to pick up the relay contacts. Accordingly the relay N releases and remains released so that its contact 56 is open. The relay N, therefore, checks response of relay P to changes in the polarity of the energy supplied over the conductors Ill and II, and contact it of relay N will not establish the circuit governed by contacts ll of relay P unless the contacts of relay P are in correspondence with the polarity of the energy supplied to the relay.

If it is not necessary to have the relay N check the relay P, or if the relay P is of the safety type which does not require checking, the relay N may be of the neutral type.

The relays P and N are selected and arranged so that on a change in the polarity of the energy supplied to the control wires I0 and II, contact it of relay N will release and interrupt the circuit controlled thereby before contact ll of relay P moves. This mode of operation may be secured by selecting the relays P and N so that relay N responds more rapidly than relay P, or it may be secured by arranging these relays so that relay P will not respond to energy supplied through the winding of relay N and will respond only to energy supplied over the shunt circuit established by back contact l8 of relay N. Since relay P will not operate until after relay N releases, contact I? of relay P is never required to interrupt the circuit governed thereby at a time when energy is being supplied over the circuit.

Fig. 2 of the drawings shows a modification of our invention for controlling a track switch W which is moved between a normal and a reverse position by means of an electric motor M. The motor drives the switch through suitable mechanism, not shown. In the system shown in Fig. 2 the motor M is of a type designed to operate on direct current supplied from a suitable source, not shown, the positive terminal of which is designated as C. Associated with motor M is an overload relay OR and control relays P and N.

The equipment is shown in the condition which it assumes when the switch W and its controlling device PC are in their normal positions and the contacts of the overload relay OR are released.

As the pole changer PC is in its normal position, relays P and N are energized by a circuit traced from the positive terminal of the source of control energy through the pole changer PC, conductor It, through the winding of relay P, normal polar contact I5 of relay P, through the win-ding of relay N from left to right, over back contact 20 of relay OR, over normal polar contact I2 of relay P, conductor I I, and pole changer PC to the: negative. terminator thesourceof: ccnetrolaenergyz.

Accordingly, relay N is picked up andrtei'ay'P isenergized to hold its leitehand: or; normal contacts closed;

Asthe switchW is in itsnormai position. con: tact 2B is out. of engagement with contact 29 and interrupts the supply of'energy furnished for the operation of the switch motor. The contact 28. is operated in accordance with the; movement of the switch and. isarrangedso' that. it engages. con.- t'act 29 in allpositions of the switch except the normal position. thereof, and so. that it enga es a. contact 2-! in: all the ositions; of the switch except the reverse. position. thereof.

It the pole changerPC iszreversed, the polarity off the energy supplied to: relays P. and N is reversed, and they operate in a manner substantially the same. as. that previously described for Fig. 1. Relay N releases, after which the con.-

tacts of relay P move from. their left-hand: position to their right-hand position. Since the relay N releases before the contacts of relay P move, the circuit for supplying energy to the switch motor M is always opened by contact 2! of relay N, thus interrupting any flow: of energy existing at that time. Since the. contacts of relay P arenever called upon to interrupt. the circuit for supplying energy to the switch motor M. they may be of a lighter-type of construction, 1

while the contacts of relay N are of the heavyduty type.

After the contacts of' relay P- have moved to their right-hand position, relay-N'picks-up, establishing the circuit to supply energy to the motor M; This circuit is traced from terminal B, over front contact 2i of relay N, reverse polar contact 22 of relay P, through motor armature 23, thermal resistance 25, over reverse polar contact 26 of relay P, switch operated contacts 21 and 28-, and through the motor field winding 3| to terminal C. The motor armature and its field winding are energized in series and the various parts are arranged so that the motor operates to move the switch W to its reverse position.

When the switch completes its movement to its reverse position, contact 28 is moved out of engagement with contact 21- to interrupt the aircuit traced above for supplying energy to the motor M and the motor ceases to operate.

When the switch is in its reverse position, if the pole changer PC is restored to its normal position, energy of normal polarity is applied to relays P and N, so that relay N will release, the contacts of relay P will move from their righthand position to their left-hand position, after which relay N picks up, in a manner similar to that described previously for operation of relays P and N when energy of reverse polarity was applied, and a circuit is established to supply energy to the motor M to cause it to. move the switch to its normalv position. This circuit is traced from terminal B, over. front contact 2.! of relay N; normal polar contact through. thermal resistance 25, motor armature 23, over normal polar contact 22 of relay P, contacts 29 and 28, and through field coil winding 3! of motor M to terminal C- Accordingly, the

motor armature and field winding are energized inseries, while the various parts are arranged so that the motor operates to move the switch to its normal position.

When the: switch completes its movement to its normal position, contact 28' is moved out of err- 26- of relay P,

Y of the winding; 33.. Accordingly,

casement with contact 29: and interrupts the traced above for supplying: energy to the motor and the motor thereupon ceases to 0116158326,.

The thermal resistance. 25 which is included in series with the circuit for supplying energy to. the switch motor has a. positive thermal. cociicicnt of resistance, that is, the resistance of uni-t: increases as the temperature of the material of which. it; is constructed increases.

Relay- QR, is; provided with a pick-up winding 32 which. is connected across resistor 25. The relay-- OR: also has a, holding winding .33, and means are provided; to shunt the holding winding whem the relay contacts are released, and to energize. the holding winding in series with the relay 1? when the overload relay contacts are picked up.

They relay OR- is, equipped with contacts of-the makes-before-break type, and as shown the righthand terminal of" the holding winding 33 is con.- nected to movable contact 35, while the contact 35, when: released, engages stationary contact 31 which is connected to the left-hand terminal as long. as the contacts of relay OR are released, the holding winding 33 of relay OR is short-circuited by the circuit controlled by contacts 35 and 31. As the winding 33 is short-circuited when the relay contacts are released,. the. relay contacts are rendered slow inv picking. up and the overload relay will; not; respond. to momentary surges in the cur-dent in the motor: circuit, as occur when the motor is started or the switch is reversed in mid-stroke.

As previously explained, the energy supplied to the. motor M is; supplied over the circuit which includes in, series therewith the resistor 2.5, while the terminals of the, pick-up winding 32 of relay OR: are connected across the resistor 25. On the supply of energy to the motor there is a voltage drop across the resistor 25 with a result that a portion of the energy supplied to the. motor is supplied through the pick-up winding 32 of relay 0R. As a result of the supply 01 energy to the motor M, the resistor 25 becomes heated and its resistance increases so that there is a correspondincrease in the. value of the current supplied through the pick-up winding 32 of relay OR.

The, various parts are so arranged and proportioned that under normal conditions most of the energy supplied. to the motor is supplied through the-resistor 2.5., while the current supplied through the winding 32 of relay OR is of too small, value to pick up the relay contacts. Accordingly, the contacts of relay OR remain released and contact 20 maintains the circuit, for connecting the winding of relay N in series with the winding of relay P so that contact 2| of, relay N; remains picked up and maintains the supply of energy to the motor until the switch completes its movement and causes contact 28 to interrupt the circuit of the switch motor.

The various parts of the equipment are also arranged and proportioned so that if the motor M draws current of unusually high value for an abnormally long period, as occurs when movement of the switch is obstructed, the resistance 25 will become heated to a temperature such that; its resistance increases to a degree effective vtocause the current supplied through the winding 32 of relay OR to be great enough to pick up. the relay contacts. 3

Q1: movement of the contacts of relay OR towards their picked-up position contact 38 engages cohtactl35 to thereby establish a circuit to energize the holding winding 33 in series with relay P, while contact 38 moves contact 35 out of en'- gagement with stationary contact 31 to interrupt the circuit short-circuiting the holding winding'33. 1 7

If the switch is being moved to its normal position at the time the overload condition occurs, the circuit for supplying energy to the winding 33 of relay OR is traced from the positive terminal of the source, through pole changer PC, conductor l0, winding of'relay P, winding 33 of relay OR from left to right, over contacts 35 and 38 of relay OR, conductor ll, and through pole changer PC to the negative terminal of the source. When the switch is being moved to its normal position the direction of current fiow through the resistor 25 is such that energy flows through the pick-up winding 32 of relay OR from left to right, and when the circuit for the holding winding 33 is completed, energy will flow through the holding winding 33 in the same direction as that flowing in the pick-up winding.

. If the switch is being moved to its reverse position at the time the overload condition occurs, the circuit for supplying energy to the winding 33 of relay OR is traced from the positive terminal of the source, through pole changer PC, conductor ll, over contacts 35 and 38 of relay R, winding of relay OR from right to left, through the winding of relay P, over conductor l0, and pole changer PC to the negative terminal of the source. At this time the direction of current flow through resistor 25 is such that energy flows through the pick-up winding 32 of relay OR from right to left, and when the circuit for the holding winding 33 is completed, energy willfiow through the holding winding 33 in the same direction as that flowing in the pick-up winding.

Accordingly, when the contacts of the overload relay OR pick up the energy supplied from'the control wires to the holding winding of relay OR always flows through this winding in the same direction as the energy which had been supplied to the relay pick-up winding. As a result, -the energy supplied to the pick-up and holding windings of this relay causes flux of the same polarity to be developed in the relay core so that on picking up of the relay contacts, and resultant supply of energy to the relay holding winding, the relay contacts are maintainedpicked up.

In addition, on picking up of the contacts of relay OR its contact 20 interrupts the supply of energy to relay N, and its contact 2| releases and interrupts the supply of energy to the switch motor. Release of contact 2| also interrupts the supply of energy to the pick-up winding of relay OR, but the contacts of this relay are maintained picked up by the holding winding of therelay so that contact 20 of relay. OR interrupts the circuit of relay N and it remains released and continues to interrupt the circuit of the switch motor.

After an overload has occurred, control of the switch may be regained by operation of the pole changer PC to its other position, causing a change in polarity of the supply of energy to the holding winding 33 of relay OR. As a result, there is a. reversal of flux polarity in the relay core, which causes the relay OR to release. When relay OR releases, its contact 2!! establishes the circuit including rectifier K and winding of relay, N, and thereafter the polar contacts of relay P move to their other position followed by the contacts "of relayN picking up. This results in the establishment of the circuit to supply energy to the motor M to cause it to move the switch to its other position. i p

In addition, on release of the contacts of relay OR, contact 38 is disengaged from contact to interrupt the circuit for supplying energy to the holding winding 33, while contact 35 engages contact 31 to establish the circuit for short-circuiting the winding 33. From the foregoing it may be seen that this system is so arranged that under any circumstances'wherein the switch does not complete its movement to one position or the other, the circuit for supplying energy to the motor M is always interrupted by contact 2| of relay N, so that the contacts of this relay may be of the heavyduty type, while the contacts of relay P, which are never called upon to interrupt the supply of energy to the .motor M, may be of a lighter construction.

Fig. 3 of the drawings shows a modification of our invention which is similar to Fig. 2 and differs therefrom in that it employs a motor MA of a type adapted to operate on alternating current, and a rectifier RA is provided to supply the pickup winding 32 of relay OR with direct current. The energy for operating the motor MA is supplied from a suitable source of alternating current, the terminals of which are designated BX and OK in the drawings.

The equipment is shown in the condition which it assumes when the switch W and its controlling device PC are in their normal positions and the contacts of'the overload relay OR. are released.

As the pole changer PC is in its normal position relays P and N are energized in series by a circuit traced from the positive terminal of the source of control energy, through the pole changer PC, conductor l0, through the winding of relay P, normal polar contact l5 of relay P, through the winding of relay N from left to right, over contact 20 of relay OR, over normal polar contact IZ- of relay P, conductor l l, and pole changer PC to the negative terminal of the source of control energy. Accordingly, relay N is picked up and relay P is energized to hold its left-hand or normal contacts closed. As the switch W is in its normal position, contact 28 is out of engagement with contact 29 and interrupts the supply of energy-to the motor MA.

If the-pole changer PC is reversed, the relays P and N operate in a manner similar to that previously described for Fig. 1. When contacts 28 and-22 of relay P move to their reverse positions and contact 2| of relay N picks up, the circuit for supplying energy to the switch motor is completed in such a manner as to cause the motor to move the switch to the reverse position. This circuit is traced from terminal BX, over contact 2| of relay N, through thermal resistance 25, reverse polar-contact 22 of relay P, armature 23 of motor MA,-reverse polarcontact 26 of relay P, over contacts 21 and 28, and through field winding 3| to terminal OK. The motor armature and its field winding are energized in series and the various parts are arranged so that the motor operates to move the switch W to its reverse position.

When the switch completes its movement to its'reverse position, contact 28 is moved out of engagement with contact 21 to interrupt the circuit traced above for supplyingenergy to the motor MA and the motor ceases to operate. I

When the 'switch is in-its reverse position, if the pole" changer PC is restored to its normal position, energy of normal polarity is applied to relays P and N, so that relay N will release, the contacts of relay-P will move from their reverse position to their normal position after which relay N picks up, in a'manner similar to that previously described for operation of relays 'P and N when energy of reverse polarity was applied, and a circuit is established to supply energy to the motor MA tocause it to move the switch to its normal position. This circuit is traced from terminal BX, over front contact H of relay N, through thermal resistance '25, normal polar contact 26 of relay P, motor armature 23, normal polar contact 22,'contacts 28 and '29, and through motor field winding 3! to terminal OK. The motor "armature and field winding are-energized in series and the various parts are arranged so that the motor operates to-move the switch W to its normal position.

When the switch completes its movement to its normalposition, contact 28 is moved out of engagement with contact 29 to interrupt the circult traced above for supplying energy to the motor MA and the motor ceases to operate.

The input terminals of rectifier RA are connected across the thermal resistance 25, while the positive output terminal is onneoted to the right-hand terminal of the pick-up winding 32 of relay OR, while the negative output terminal ofrectifier RA is connected to the left-hand terminal oi pick-unwinding 32 of relay OR. The holding winding 33 is supplied with energy from the control circuit in series with relay P, and is reversibly connected with thecontrol wires by the polar contacts of relay P so that the flow of enany in the holding winding when relay OR picks up is always the same direction as the direction of flow of'energy in the pick-up winding, that is, from right to left. The contact :equip ment is similar and functions similarly to that previously described for relay OR in Fig. 2.

As previously explained, the voltage drop across resistor 25 increases the :motor M draws a high value of current foran unusually long period of time, and the now of rectified current supplied to the pick-up winding .32 of relay OR, through rectifier RA becomes great enough to pick up relay B, which is then held up by the circuit supplying energy to its holding winding 33.

If the switch is beingmoved to its normal position at the time the overload occurs, the circuit for supplying energy to the holding winding 33 of relay OR is traced from the positive terminal of the source through pole changer contact 8, conductor ,Hl, winding :of relay P, normal polar contact i .of relay P over contacts 38 and 35 of relay OR, through the winding .33 of relay OR from right to left, over normal polar contact l2 of relay P, .and through :conductor H and contact 9 of pole changer PC to the negative terminal of the source.

If the switch is being moved to its reverse position at the time the overload condition occurs, the circuit for supplying energy to the holding winding .33 of relay OR is traced from the positive terminal of the source through contact 8 of pole changer PC, conductor l l over reverse polar contact 1.2 of relay P, contacts 35 and 38 of relay OR, through winding 33 of relay OR. from right to left, over reverse polar contact of relay P, through the winding of relay P, conductor 1:0, and over contact 9 of pole changer PC to the negative terminal of the source.

' It will be "seen, therefore, that on picking up of the contacts 50f relay OR :a circuit is established to energize the holding winding 33 of relay OR in series with relay P from the conductors H! and l l and that regardless of the polarity of the energy supplied to the control wires at the time the overload relay picks up, the energy flows through the winding 33 from its right-hand terminal to its left-hand terminal.

The pick-up winding 32 of relay OR is connected to rectifier RA so that energy always flows throughthis winding from its right-hand to its left-hand terminal.

Accordingly, the energy supplied to the pick-up and holdin windings of the overload relay OR always flow-s through these windings in the same direction'a-t the time the overload relay picks up, and as a result flux of the same polarity is developed in the relay co-re, so that on picking up of the relay contacts, and resultant supply of energy to the relay holding winding, the relay contacts are maintained picked up.

In addition, on picking up of the contacts of relay OR its contact 29 interrupts the supply of energy to relay N so that contact 24 of relay N releases and interrupts the supply of energy to the motor MA. Release of contact 2| also interrupts the supply of energy to the pick-up winding 32 of relay OR, but the contacts of this relay are maintained picked up by the holding winding of the relay so that contact 25? of relay OR interrupts the circuit of relay N and it remains released and continues to interrupt the circuit of the switch motor.

After an overload has occurred, control of the switch may be regained by operation of the pole changer PC toits other position, causing a change in the polarity of the energy supplied to the holding winding 33 of relay OR, which results in a change of polarity of the flux in the core of relay OR, whereupon relay OR releases and its contact 2!! establishes the circuit including rectifier K and relay N and thereafter the polar contacts of relay P move to their other position followed by the picking up of relay N. This results in the establishment of the circuit; to supply energy to the motor MA which operates to move the switch to its other position.

in addition, on release of the contacts of relay OR contact 38 is disengaged from contact 35 to interrupt the circuit for supplying energy to the holding winding 33, while contact 35 engages con- 3! to establish the circuit for short-circuiting the winding 33.

From the foregoing it will be seen that our invention provides means for controlling a polar relay and a neutral relay in such a manner that on a change in the polarityof the energy supplied to the control circuit -for the relays the neutral relay releases prior to the movement of the contacts of the polar relay and the neutral relay will not pick up unless the position of the polar relay contacts is in agreement with the polarity of the energy supplied to the relays. It will also be seen that this invention provides means for controlling electric switch motors in such a manner that in any case of the motor circuit being interrupted before the switch completes its movement to one position or the other, the contacts of the neutral circuit will interrupt the motor circuit, rather that the contacts of the polar relay.

Although we have herein shown and described only three forms of circuits embodying our invention, it is understood that various changes and modifications may he made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

1. In combination, a pair of control conductors to which energy of one polarity is supplied at times and to which energy of the other polarity is supplied at other times, a polarized relay having one terminal of its winding connected to one of said control conductors, an auxiliary relay having normally released contacts which become picked up when and only when energy flows through the relay winding from its first to its second terminal,'an asymmetric unit connected across the winding of the auxiliary relay by a back contact or said auxiliary relay and poled to permit energy to flow from the second to the first terminal of said winding, and means governed by polar contacts of said polarized relay for reversibly connecting the auxiliary relay windin and said asymmetric unit in multiple between the other terminal of the polarized relay winding and the other one of said control conductors, said means being arranged so that energy from said control conductors fiows through the Winding of said auxiliary relay from its first to its second terminal when and only when the position of the contacts of said polarized relay and the polarity of the energy supplied to said control conductors are in correspondence, said polarized and auxiliary relays being selected so that the contacts of the Polarized relay will not be operated between their two positions in response to energy of the value supplied to the relay winding through the Winding of said auxiliary relay but will be operated by energy of the value supplied through said asymmetric unit, and a circuit governed by a front con tact of said auxiliary relay and by a polar contact of said polarized relay.

2. In combination, a pair of control conductors to which energy of one polarity is supplied at times and to which energy of the other polarity is supplied at other times, a polarized relay having one terminal of its winding connected to one of said control conductors, an auxiliary relay having normally released contacts which become picked up when and only when energy flows through the relay winding from its first to its second terminal, an asymmetric unit connected across the winding of the auxiliary relay by a back contact of said auxiliary relay and poled to permit energy to'fiow from the second to the first terminal of said winding, and means governed by polar contacts of said polarized relay for reversibly connecting the auxiliary relay winding and said asymmetric unit in multiple between the other terminal of the polarized relay winding and the other one of said control conductors, said means being arranged so that energy from said control conductors flows through the winding of said auxiliary relay from its first to its second terminal when the position of the contacts of said polar relay and the polarity of the energy supplied to said control conductors are in correspondence.

3. In combination, a pair of control conductors to which energy of one polarity is supplied at times and to which energy of the other polarity is supplied at other times, a polarized relay having one terminal of its winding connected to one of said control conductors, an auxiliary relay, means governed by polar contacts of said polarized relay for reversibly connecting the winding of said auxiliary relay between the other terminal of the polarized relay winding and the other of said control conductors, an asymmetric unit in series with a back contact of said auxiliary relay connected across the winding of said auxiliary relay, said asymmetric unit being arranged so that energy flows from said control conductors through said'asymmetric unit when said auxiliary relay is released and the position of the contacts of said polarized relay and the polarity of the energy supplied to said control conductors are out of correspondence, and a circuit governed by a contact of said auxiliary relay and by a contact of said polar relay.

4. In combination, a pair of control conductors to which energy of one polarity is supplied at times, and to which energy of the other polarity is supplied at other times, a polarized relay having one terminal of its winding connected to one of said control conductors, an auxiliary relay, means governed by polar contacts of said polarized relay for reversibly connecting the Winding of said auxiliary relay between the other terminal of the polarized relay winding and the other of said control conductors, an asymmetric unit in series with a back contact of said auxiliary relay. connected across the winding of said auxiliary relay, said asymmetric unit being arranged so that energy flows from said control conductors through said asymmetric unit when said auxiliary relay is released and the position of the contacts of said polar relay and the polarity of the energy supplied to said control conductors are out of correspondence, said polarized and auxiliary relays being selected so that the contacts of the polarized relay will not be operated between their two positions in response to energy of the value supplied to the relay winding through the winding of said auxiliary relay but will be operated by energy of the value supplied through said asymmetric unit, and a circuit governed by a'front contact of said'auxiliary relay and by a polar contact of said polarized relay.

5. In combination, a pair of control conductors to which energy of one polarity is supplied at times and energy of the other polarity is supplied at other times, a polarized relay having one terminal of its winding connected to one of said control conductors, an auxiliary relay, and means including polar contacts of said polarized relay for reversibly connecting the winding of the auxiliary relay between the other terminal of the winding of the polarized relay and the other control conductor, saidmeans being efiective in each position of the contacts of said polarized relay provided a back contact of said auxiliary relay is closed to connect in multiple with the winding of the auxiliary relay and in series with the winding of the polarized relay an asymmetric unit poled to permit flow of energy therethrough when the position of the polarized relay contacts and the polarity of energy supplied to said control conductors are out of correspondence.

6. In combination, a pair of control conductors to which energy of one polarity is supplied at times and to which energy of the other polarity is supplied at other times, a polarized relay, an auxiliary relay having normally released contacts which become picked up when and only when energy flows through the relay winding from its first to its second terminal, means governed by polar contacts of said polarized relay for supplying energy from said control conductors to the winding of said auxiliary relay in such a manner that energy flows through the winding of said auxiliary. relay iromlits first terminal to its second terminal when and only when the polar contacts of said polarized relay are in correspondence with the polarity of energy supplied by said control conductors, circuit means including a back contact of said auxiliary relay for supplying from said control conductors to the winding of said polarized relay energy efiective to operate the contacts of said polarized relay, and a circuit governed by a front contact of said auxiliary relay and by a polar contact of said polarized relay.

"1'. In combination, a pair of control conductors to which energy of one polarity is supplied at times and to which energy of the other polarity is supplied at other times, a polarized relay, an auxiliary relay having normally released contacts which become picked up when and only when energy flows through the relay winding from its first to its second terminal, means governed by polar contacts of said polarized relay for supplying energy from said control conductors to the winding of said auxiliary relay in such a manner that energy flows through the winding of said auxiliary relay from its first terminal to its second terminal when and only when the polar 14 contacts of said polarized relay are in correspondence with the polarity of energy supplied by said control conductors, circuit means effective when and only when said auxiliary relay is released for supplying from said control conductors to the winding of said polar relay energy efiective to operate the relay contacts, and a circuit governed by a front contact of said auxiliary relay and by a polar contact of said polarized relay.

ALLAN T. JOHNSTON.

ARTHUR L. JEROME.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,250,214 Ashworth July 22, 1941 2,312,038 Hines et al. Feb. 23, 1943 2,340,752 Hufnagel Feb. 1, 1944 2,347,602 Johnston Apr. 25, 1944 2,394,111 Schaelchlin Feb. 5, 1946 

